My primary MySQL server has been VERY overloaded lately (which is the main reason new blades are on the way), but today I decided to see what I can do about it in the meantime (the parameters have already been tuned as much as possible).
First I toyed around with a single node MySQL Cluster… it didn’t work terribly well. I think you really need 2 or 4 nodes for it to be effective.
Then I decided to run two different copies of mysqld on the same machine. Dude, this works *so* well under a high load that it’s almost unbelievable. While the memory fragmentation issues are still there, it’s 20x better (really). I should have done this a long time ago… 🙂